Development of a Mixture Design Procedure for Stone Matrix Asphalt

Details

• Creators:
  Brown, E.R. ; Haddock, John E. ; Mallick, Rajib B. ; Lynn, Todd A.
• Subject/TRT Terms:
  • Asphalt mixtures
  • Test procedures
  • Superpave
• DOI:
  https://doi.org/10.21949/1404497
• Resource Type:
  Tech Report
• Geographical Coverage:
  Alabama;United States
• Corporate Publisher:
  National Center for Asphalt Technology (U.S.)
• Abstract:
  Stone Matrix Asphalt (SMA) has been used successfully in Europe for over 20 ; years to provide better rutting resistance and to resist studded tire wear. ; Since 1991, the use of SMA has increased steadily in the United States. At ; present, some states routinely use SMA even though a standard mixture design ; procedure is not available. A mixture design procedure that provides guidance ; on material properties, aggregate gradation, determination of optimum asphalt ; content, and mixture properties is needed. This paper presents a mixture design ; procedure for SMA mixtures developed by the National Center for Asphalt ; Technology. Data for the development of the procedure was collected from a ; laboratory study conducted with various samples of aggregates, fillers, asphalt ; binders, and stabilizing additives. Compacted mixtures were tested to evaluate ; the effects of aggregate structure, asphalt binder, and binder-fine aggregate ; mortar. Specific conclusions from this study were: (1) The Los Angeles abrasion ; loss showed good correlation with aggregate breakdown, (2) It appeared that the ; 3:1 or 2:1 flat and elongated particles provided much better classification for ; the various aggregates than a 5:1 ratio, (3) The flat and elongated particle ; ratio showed excellent correlation with aggregate breakdown, (4) In a SMA mix, ; the percent passing the 4.75 mm sieve must be below 30 percent to ensure proper ; stone-on-stone contact, (5) The percent passing the 0.02 mm sieve did not show ; a correlation with mortar stiffness. However, the dry compacted volume, as ; obtained from the Penn State test method, did show a good correlation with ; mortar stiffness and can be utilized to characterize the shape of fillers. ; Generally, a more angular filler tends to produce a higher air voids result in ; this test, (6) In-place results from about 86 projects showed that very little ; rutting has occurred in SMA pavements constructed in the United States since ; 1991. However, for the pavements with air voids falling below the 3 percent ; range, some rutting was observed. (7) A VMA significantly lower than specified ; VMA can be obtained due to aggregate breakdown. Hence, the mix designer must ; consider aggregate type, compactor type and compactive effort along with the ; gradation in meeting the required VMA criteria. Specifying a minimum asphalt ; content can result in different requirements for aggregates with different ; specific gravity, (8) Fifty blows of Marshall hammer were found to be ; approximately equal to 100 revolutions of the Superpave gyratory compactor in ; terms of resultant density. The Superpave gyratory compacter was found to ; produce less aggregate breakdown than the Marshall hammer, (9) Fiber stabilizers ; were found to be more effective in reducing draindown than polymer stabilizers. ; However, mixes modified with polymer showed better resistance to rutting in ; laboratory wheel tracking tests.
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• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/13192/dot_13192_DS1.pdf
• File Type:
  [PDF - 243.94 KB]
• Collection(s):
  US Transportation Collection ; Federal Highway Administration
• Main Document Checksum:
  urn:sha-512:2dbe3ee09400c1b59159d89d5a1503a9cf4fa4cd41b4b2c04e06210875fa2be19d181cc410d5e44a1fb76c1142f1e162349a49a9d7acbfcfacfab5e16654480d